1. Field of the Invention
The present invention relates to an apparatus for use in extension or retraction of an antenna out of and into a portable communication terminal, and more particularly to a micro antenna driving apparatus adapted to extend or retract an antenna according to rotation of a motor body thereof in contact with the antenna.
2. Description of the Related Art
In general, portable communication terminals comprise various shapes of antennas. The antennas serve to improve transmission and reception sensitivity of the portable communication terminals. Such an antenna is usually retracted into a housing of the portable communication terminal, such that it can be extended out of the housing whenever it is necessary.
In a state wherein the antenna is extended out of the housing of the portable communication terminal, the antenna is connected to the portable communication terminal by passing through an antenna casing installed at an upper end of the housing, thereby serving to improve transmission and reception sensitivity of the portable communication terminal.
Although the antenna is generally configured so as to be manually extended out of the housing in use, for maximizing the convenience of use, the antenna may be configured such that it can be automatically extended or retracted under the operation of driving means.
As shown in FIG. 1, the conventional antenna driving system of a mobile phone comprises a driving roller 102, a driven roller 104, an antenna 106, a decelerator module 110, and a flexible connection member 130.
The driving roller 102 and the driven roller 104 have respective shafts 102a and 104a, which are rotatably fitted in a main bracket 108. The antenna 106 is interposed between the driving roller 102 and the driven roller 104, such that it is pushed down by the driven roller 104 to press an outer peripheral surface of the driving roller 102.
The driving roller 102 is adapted to be driven by means of the decelerator module 110 installed at a lateral side of the main bracket 108. The decelerator module 110 comprises a driving motor 112 and a plurality of reduction gears.
The flexible connection member 130 is installed between a driving shaft (not shown) of the above described decelerator module 110 and the shaft 102a of the driving roller 102. Such a flexible connection member 130 effectively transmits rotation power generated from the decelerator module 110 to the driving roller 102, even if the driving shaft (not shown) of the decelerator module 110 is not aligned on the same axis as the shaft 102a of the driving roller 102.
As can be seen from FIG. 2, if the decelerator module 110 is driven to generate the rotation power, the rotation power is transmitted to the shaft 102a of the driving roller 102 through the flexible connection member 130, resulting in rotation of the driving roller 102.
As the driving roller 102 rotates as stated above, the antenna 106, interposed between the driving roller 102 and the driven roller 104, linearly moves such that it is extended or retracted out of or into a housing 101 of the mobile phone.
The above described the antenna driving system of a mobile phone according to the prior art, however, has a problem as follows.
As shown in FIG. 2, since the antenna driving system of a mobile phone comprises the decelerator module 110, and the main bracket 108 containing the driving roller 102 and driven roller 104, it requires an excessively large installation space.
In order to solve the above problem, it has been proposed to decrease the sizes of the driving roller 102 and the driven roller 104, and consequently the main bracket 108.
However, if the sizes of the driving roller 102 and the driven roller 104 decrease, and thus diameters thereof also decrease, it inevitably requires increasing the revolutions per minute of both the driving roller 102 and the driven roller 104 for the extension or retraction of the antenna 106. This causes the antenna 106 to excessively repeatedly come into contact with outer peripheral surfaces of the rollers 102 and 104, resulting in rapid wear of the rollers 102 and 104.
Further, since the rollers 102 and 104 are made of a rubber material in order to endow the antenna 106 with a prescribed frictional force, when the antenna 106 is pushed down by the driven roller 104 to press the outer peripheral surface of the driving roller 102, the rollers 102 and 104 may be permanently deformed, resulting in a deterioration in operational stability of the antenna 106.